Isolation of Arsenic-Resistant Bacteria from Bengal Delta Sediments and their Efficacy in Arsenic Removal from Soil in Association with Pteris vittata

Abstract

The potential of arsenic-resistant bacteria in association with Pteris vittata to reduce the level of arsenic from soil was studied. The physicochemical characteristics of contaminated paddy soil were analyzed, and 3 bacterial isolates amongst 11 were screened and were selected for further study. These three isolates were characterized by 16S rDNA sequencing and identified as Bacillus altitudinis Strain SS8 (KJ432582), Bacillus megaterium Strain SS9 (KJ432583) and Lysinibacillus sp. Strain SS11 (KJ432584). Of these, Lysinibacillus sp. Strain SS11 displayed arsenic tolerance of 3256 mg L⁻¹ for arsenate and 1136 mg L⁻¹ for arsenite. Additionally, it showed bioaccumulation capacity of 23.43 mg L⁻¹ for arsenate and 5.65 mg L⁻¹ for arsenite. It also showed resistance to other heavy metals, especially towards iron, copper and chromium. It was also observed that Pteris vittata was able to take up more arsenic and iron from soil in the presence of these bacterial strains than in their absence, leading to contaminant-free soil. Thus, this system appears to be an effective bioremediating process to remove arsenic from contaminated soil.

Keywords:

• arsenic-resistant bacteria
• bioaccumulation
• bioremediation
• biotransformation
• Pteris vittata

Acknowledgments

Authors thank Mr. Rajat Pal and Mr. Harish Sharma, University of Calcutta for giving his valuable comments for the preparation of this article. Authors would also like to thank Dr. Sudha Gupta of University of Kalyani for providing taxonomical identification of Pteris vittata. Lastly, a vote of thanks to the IISER-K core facility (ICP-MS Analysis) along with Ms. Neelam Gurung for initiating the work.

Funding

SB acknowledges Department of Science and Technology, Government of India for providing Ramanujan Fellowship Research Grant, (SR/S2/RJN-09/2011) to carry this research. AS and AB are thankful to DST and UGC - CSIR for providing INSPIRE (IF130211) in the form of SRF and JRF Fellowship (23/12/2012(ii)EU-V) respectively.